JP6680587B2 - Stretchable film, method for producing the same, and composite sheet - Google Patents

Description

  The present invention relates to a stretchable film, a method for producing the stretchable film, and a composite sheet having a layer made of a stretchable film and a layer made of a nonwoven fabric.

  In the hygiene field (sanitary products, incontinence products, etc.), the medical field (surgical drapes, etc.), etc., elastic composite sheets obtained by laminating an elastic film containing a thermoplastic elastomer and a nonwoven fabric are widely used. .

Since the thermoplastic elastomer has strong adhesiveness, the stretch films and the composite sheets may come into close contact with each other and may be difficult to peel off, so-called blocking may occur.
As the stretchable film in which the occurrence of blocking is suppressed, for example, the following have been proposed.
(1) An elastic film having an elastomer layer containing a thermoplastic elastomer and a surface layer containing a thermoplastic resin provided on both the first surface and the second surface of the elastomer layer (Patent Document 1).

International Publication No. 2016/013577

However, since the elastic film (1) has a surface layer having no elasticity, the elasticity is slightly insufficient.
The present invention provides a stretchable film that suppresses blocking and has good stretchability, a method for producing the stretchable film, and a composite sheet.

The present invention has the following aspects.
<1> A surface containing an elastomer layer containing a thermoplastic elastomer and a thermoplastic resin (excluding the thermoplastic elastomer) provided on one or both of the first surface and the second surface of the elastomer layer. A stretchable film having a layer; the stretchable film is adjacent to the first region and has a band-shaped first region extending along the surface direction of the stretchable film, and is less likely to stretch than the first region. Alternately having band-shaped second regions extending along the surface direction of the stretchable film; the following average elongation ratio of the first region is 1.51 to 5.00 times, and the second region A stretch film having the following average elongation ratio of 1.01 to 1.50 times.
(Average elongation rate)
A strip-shaped test piece of 50 mm in the longitudinal direction of the first region and the second region and 100 mm in the direction orthogonal to the longitudinal direction is cut out from the elastic film. The test piece is fixed to the grip of the test apparatus so that the distance between the grips is 30 mm. The test piece is elongated in a direction orthogonal to the longitudinal direction of the first region and the second region at a speed of 100 mm / min so that the elongation calculated by the following formula (I) is 80%. The extension ratio (fold) is calculated from the following formula (III). The expansion ratios of twelve randomly selected areas in both the first area and the second area are calculated, and the average value is obtained.
Elongation = (L1-L0) / L0 × 100 (I)
Expansion ratio = R1 / R0 (III)
However, L0 is the distance between grips (mm) before extending, L1 is the distance between grips (mm) after extending, and R0 is the first region or the second before extending. Is a length (μm) in the direction orthogonal to the longitudinal direction of the region (1), and R1 is a length (μm) in the direction orthogonal to the longitudinal direction of the expanded first region or the second region ( However, R0 and R1 are measured at the same location in the same region).
<2> The stretchable film according to <1>, which is a porous stretchable film having a plurality of through holes formed therein.
<3> The stretchable film according to <1> or <2>, wherein the surface layer further contains an inorganic filler.
<4> A method for producing the stretchable film according to any one of the above <1> to <3>; a first shaping roll having a plurality of ridges extending in a circumferential direction or an axial direction; and the first shaping roll. The second ridge having a plurality of ridges extending in the same direction as the ridge of the shaping roll meshes with the ridge of one shaping roll and the groove between the ridges of the other shaping roll. As described above, the unstretched elastic film described below is passed between the first shaping roll and the second shaping roll while rotating so as to face each other, and thus the ridges of the first shaping roll. A method for producing a stretchable film, comprising the step (d) of forming the first region stretched between the ridge and the ridge of the second shaping roll and the second region not stretched.
(Unstretched elastic film)
An elastomer layer containing a thermoplastic elastomer, and a surface layer containing a thermoplastic resin (excluding the thermoplastic elastomer) provided on one or both of the first surface and the second surface of the elastomer layer. An unstretched stretchable film having.
<5> Prior to the step (d), the method further includes a step (c) of forming a plurality of depressions scattered on the unstretched stretchable film by embossing the unstretched stretchable film; In (d), the first region stretched and the second region not stretched are formed between the ridges of the first shaping roll and the ridges of the second shaping roll. At the same time, the method for producing a stretchable film according to <4>, wherein the hollow portion is stretched to form a through hole.
<6> The method for producing a stretchable film according to <5>, wherein the following permanent set of the unstretched stretchable film is 15% or more.
(Permanent strain of unstretched stretch film)
A strip-shaped test piece of 50 mm in the machine direction (MD) and 200 mm in the width direction (TD) is cut from the unstretched stretchable film. The test piece is fixed to the grip of the test apparatus so that the distance between the grips is 100 mm. The test piece is stretched in TD at a speed of 100 mm / min so that the elongation calculated by the following formula (I) is 80%, and then the test piece is immediately contracted at the same speed. Permanent strain (%) is calculated from the following formula (II).
Elongation = (L1-L0) / L0 × 100 (I)
Permanent strain = (L2-L0) / (L1-L0) × 100 (II)
However, L0 is the distance between grips (mm) before extension, L1 is the distance between grips (mm) after extension, and L2 is the load (N / It is the distance (mm) between the grips when 50 mm) becomes zero.
<7> A composite sheet having a layer made of the stretchable film according to any one of the above <1> to <3> and a layer made of a nonwoven fabric.

The stretchable film of the present invention suppresses the occurrence of blocking and has good stretchability.
According to the method for producing a stretchable film of the present invention, it is possible to produce a stretchable film in which the occurrence of blocking is suppressed and the stretchability is good.
In the composite sheet of the present invention, the occurrence of blocking due to the layer made of a stretchable film is suppressed, and the stretchability is good.

It is the photograph which looked at an example of the elastic film of the present invention from the upper surface. It is an enlarged photograph of the elastic film of FIG. 2 is an enlarged photograph of the stretchable film of FIG. 1 stretched so as to have a TD stretch of 80%. It is sectional drawing which shows an example of the unstretched elastic film used for manufacture of the elastic film of this invention. It is an enlarged view showing an example of a pair of shaping rolls. It is an enlarged view showing other examples of a pair of shaping rolls.

The following definitions of terms apply throughout the specification and claims.
"Thermoplastic elastomer" has properties similar to those of vulcanized rubber at the operating temperature, disappears at the processing temperature, can be easily processed, and returns to the operating temperature at its original properties. Means a coalesced or polymer blend.
The term "thermoplastic resin" means a synthetic resin that can be molded into a thermoplastic resin by heating. However, in the present invention, the thermoplastic resin does not include a thermoplastic elastomer.
“The second region is less likely to be stretched than the first region (the first region is more likely to be stretched than the second region)” means that the stretch film is in the longitudinal direction of the first region and the second region. When stretched in a direction orthogonal to, the elongation (%) of the second region is smaller than the elongation (%) of the first region (the elongation of the first region is greater than the elongation (%) of the second region). (%) Is large).

<Elastic film>
The stretchable film of the present invention is a thermoplastic resin (excluding a thermoplastic elastomer) provided on one or both of an elastomer layer containing a thermoplastic elastomer and a first surface and a second surface of the elastomer layer. And a surface layer containing.
The stretchable film of the present invention is a strip-shaped first region extending along the surface direction of the stretchable film, and adjacent to the first region, less likely to stretch than the first region, along the surface direction of the stretchable film Alternately extending strip-shaped second regions are provided.
The stretchable film of the present invention may be a porous stretchable film having a plurality of through holes formed therein.

FIG. 1 is a photograph of a porous stretchable film, which is an example of the stretchable film of the present invention, seen from above, and FIG. 2 is an enlarged photograph of the stretchable film of FIG.
The porous stretchable film 10 includes an elastomer layer, a first surface layer provided on the first surface of the elastomer layer, and a second surface layer provided on the second surface of the elastomer layer (hereinafter referred to as “first surface layer”). The surface layer and the second surface layer are collectively referred to simply as the surface layer.). Illustration of the cross section of the porous stretchable film 10 is omitted.

In the porous stretchable film 10, strip-shaped first regions 11 extending in MD and strip-shaped second regions 12 extending in MD are alternately formed in TD to form a striped pattern.
The through holes 13 are formed at equal intervals in the length direction of each first region 11, and are arranged in a staggered manner in the entire porous stretchable film 10.
In FIGS. 1 and 2, since the background is black, the first area 11 is seen as an opaque white portion, the second area 12 is seen as a transparent gray portion, and the through hole 13 is shown as a black portion. appear.

(Elastomer layer)
The elastomer layer is a layer that imparts elasticity to the stretch film.
The elastomer layer may be a single layer or multiple layers.

The elastomer layer includes a thermoplastic elastomer.
The elastomer layer may contain other components, if necessary, within a range that does not impair the effects of the present invention.

Thermoplastic elastomer:
Examples of the thermoplastic elastomer include olefin-based thermoplastic elastomer, styrene-based thermoplastic elastomer, urethane-based thermoplastic elastomer, and polyester-based thermoplastic elastomer. When the thermoplastic resin in the surface layer is an olefin resin, an olefin thermoplastic elastomer is preferable from the viewpoint of compatibility.

The thermoplastic elastomer is composed of hard segments and soft segments.
Examples of the hard segment of the olefinic thermoplastic elastomer include polyethylene and polypropylene. Examples of the soft segment of the olefin thermoplastic elastomer include ethylene propylene rubber (EPDM, EPM, EEM), hydrogenated (styrene) butadiene rubber, polyoctene, and the like.
Examples of the hard segment of the styrene-based thermoplastic elastomer include polystyrene. Examples of the soft segment of the styrene-based thermoplastic elastomer include polybutadiene, polyisoprene, polyethylene, and hydrogenated products thereof.

Examples of commercially available olefin-based thermoplastic elastomers include the following.
Vistamaxx (registered trademark) 6102 (manufactured by ExxonMobil, propylene-ethylene copolymer, glass transition temperature: -32 ° C, ethylene unit content: 16% by mass),
Vistamaxx (registered trademark) 3020 (manufactured by ExxonMobil, propylene-ethylene copolymer, glass transition temperature: -26 ° C, ethylene unit content: 11% by mass),
Infuse (registered trademark) 9107 (manufactured by Dow Chemical Co., ethylene-octene copolymer, glass transition temperature: -62 ° C),
Infuse (registered trademark) 9507 (manufactured by Dow Chemical Company, ethylene-octene copolymer, glass transition temperature: -62 ° C) and the like.
The thermoplastic elastomer may be used alone or in combination of two or more.

Other ingredients:
Other components include thermoplastic resins (excluding thermoplastic elastomers), inorganic fillers, amide-based antiblocking agents (stearic acid amide, etc.), antioxidants, weather resistance stabilizers, antistatic agents, antifogging agents, Examples include metal soaps, waxes, fungicides, antibacterial agents, nucleating agents, flame retardants, lubricants and the like.

Examples of the thermoplastic resin include olefin resins such as polyethylene and polypropylene.
Examples of the inorganic filler include calcium carbonate, zeolite, silica and the like.
Other components may be masterbatched and added to the material for forming an elastomer layer.
As the other components, one type may be used alone, or two or more types may be used in combination.

Ratio of each component in the elastomer layer:
The proportion of the thermoplastic elastomer is preferably 70% by mass or more and more preferably 80% by mass or more based on 100% by mass of the elastomer layer. When the proportion of the thermoplastic elastomer is at least the lower limit value of the above range, excellent stretchability can be easily obtained. The upper limit of the proportion of the thermoplastic elastomer is 100% by mass.

  The proportion of the thermoplastic resin (excluding the thermoplastic elastomer) is preferably 0 to 20 mass% in the total 100 mass% of the resin components in the elastomer layer. When the proportion of the thermoplastic resin is at most the upper limit value of the above range, excellent stretchability is easily obtained.

Elastomer layer thickness:
The thickness of the elastomer layer is preferably 5 to 50 μm, more preferably 10 to 45 μm, still more preferably 15 to 40 μm. When the thickness of the elastomer layer is at least the lower limit value of the above range, the stretchable force of the stretchable film is sufficiently obtained, and thus the shrinkage force when the stretchable film is applied to a product is sufficiently obtained. When the thickness of the elastomer layer is not more than the upper limit of the above range, it is possible to prevent the stretching force of the stretch film from becoming excessive and the shrinkage force when applied to a product becoming too strong.
When the elastomer layer is a multilayer, the thickness of the elastomer layer is the thickness of the entire multilayer.

(Surface layer)
The surface layer is a layer that suppresses the occurrence of blocking of the stretch film.
The surface layer is provided on either or both of the first surface and the second surface of the elastomer layer. From the viewpoint that the occurrence of blocking of the stretch film can be sufficiently suppressed, it is preferably provided on both the first surface and the second surface of the elastomer layer. The first surface layer provided on the first surface and the second surface layer provided on the second surface of the elastomer layer may be the same kind of surface layer or different kinds of surface layers. May be.

The surface layer contains a thermoplastic resin (excluding the thermoplastic elastomer).
The surface layer preferably further contains an inorganic filler.
The surface layer may contain other components, if necessary, within a range that does not impair the effects of the present invention.

Thermoplastic resin:
As the thermoplastic resin, those having compatibility with the thermoplastic elastomer in the elastomer layer are preferable. When the thermoplastic elastomer in the elastomer layer is an olefinic thermoplastic elastomer, an olefinic resin such as polyethylene or polypropylene is preferable from the viewpoint of compatibility.
The thermoplastic resins may be used alone or in combination of two or more.

Inorganic filler:
The inorganic filler is a component that imparts slipperiness to the surface of the surface layer and further suppresses the occurrence of blocking of the stretch film.
Examples of the inorganic filler include calcium carbonate, zeolite, silica and the like.
The inorganic filler may be used alone or in combination of two or more.

The average particle diameter of the inorganic filler is preferably 2 to 10 μm. When the average particle size of the inorganic filler is at least the lower limit value of the above range, the slipperiness is improved. When the average particle diameter of the inorganic filler is not more than the upper limit value of the above range, the touch will be good.
The average particle diameter of the inorganic filler is an average value of particle diameters of 10 particles randomly selected in the scanning electron microscope image.

  The inorganic filler may be masterbatched and added to the surface layer forming material. Further, the masterbatch of the inorganic filler may be directly used as the surface layer forming material. Examples of the base resin of the masterbatch include olefin resins such as polyethylene and polypropylene, and polyethylene is preferable from the viewpoint of versatility.

Examples of commercially available inorganic batch masterbatches include the following.
TEP 1HC783 WHT (manufactured by HANIL TOYO, calcium carbonate (average particle diameter: 5 μm, content rate: 50% by mass), base resin: polyethylene),
PE180NLD2 (Samplac Industry Co., Ltd., calcium carbonate (average particle diameter: 5 μm, content rate: 50 mass%), base resin: polyethylene),
Quinoplus EMB-7A2806AC (manufactured by Sumika Color Co., Ltd., zeolite (average particle diameter: 2 μm, content rate: 20 mass%), base resin: polyethylene),
Smooth Master S (manufactured by Dainichiseika Kogyo Co., Ltd., silica (average particle diameter 10 μm, content rate: 20 mass%), base resin: polyethylene) and the like.
The masterbatch may be used alone or in combination of two or more.

Other ingredients:
Other components include amide-based antiblocking agents (stearic acid amide, etc.), antioxidants, weathering stabilizers, antistatic agents, antifogging agents, metal soaps, waxes, fungicides, antibacterial agents, nucleating agents, Examples include flame retardants and lubricants.

Other components may be masterbatched and added to the surface layer forming material.
Examples of the masterbatch of the amide-based antiblocking agent include Rikemaster EXR-040 (manufactured by Riken Vitamin Co., masterbatch containing stearic acid amide (stearic acid amide content: 15% by mass), base resin: polyethylene).
As the other components, one type may be used alone, or two or more types may be used in combination.

Ratio of each component in the surface layer:
The proportion of the thermoplastic resin is preferably 10 to 90% by mass, and more preferably 15 to 85% by mass, based on 100% by mass of the surface layer. If the ratio of the thermoplastic resin is at least the lower limit value of the above range, the surface layer can be formed.
The thermoplastic resin also includes a masterbatch base resin.

  The proportion of the inorganic filler is preferably 10 to 90% by mass and more preferably 15 to 85% by mass based on 100% by mass of the surface layer. When the proportion of the inorganic filler is at least the lower limit value of the above range, the occurrence of blocking of the stretch film can be sufficiently suppressed. Further, the surface layer is easily broken during the gear stretching described later. When the proportion of the inorganic filler is at most the upper limit value of the above range, the surface layer can be formed.

Surface layer thickness:
The thickness of the surface layer is preferably 0.5 to 10 μm, more preferably 2 to 9 μm, and further preferably 3 to 8 μm. When the thickness of the surface layer is at least the lower limit value of the above range, the occurrence of blocking of the stretch film can be sufficiently suppressed. When the thickness of the surface layer is not more than the upper limit value of the above range, the stretchability of the stretchable film is sufficiently obtained. The first surface layer provided on the first surface of the elastomer layer and the second surface layer provided on the second surface may have the same thickness or different thicknesses.

(First area and second area)
The first region is a portion where the surface layer is stretched and broken when the unstretched stretchable film is stretched in a stripe shape by the gear stretching described below.
The second region is a portion where the surface layer was not stretched and broken when the unstretched stretchable film was stretched in a stripe shape by gear stretching described later.

In the first region, although the surface layer remains, the surface layer is stretched and broken, and therefore the stretchability is close to that of the elastomer layer alone.
In the second region, the surface layer is not stretch-broken, that is, the non-stretchable surface layer remains on the surface of the elastomer layer, and thus the stretchability is somewhat insufficient.
Therefore, the second region is less likely to expand than the first region, and the first region is easier to expand than the second region.

The following average extension ratio of the first region is 1.51 to 5.00 times, and preferably 1.60 to 4.50 times.
The following average expansion ratio of the second region is 1.01 to 1.50 times, and preferably 1.01 to 1.48 times.

Average elongation ratio:
A strip-shaped test piece of 50 mm in the longitudinal direction of the first region and the second region and 100 mm in the direction orthogonal to the longitudinal direction is cut out from the elastic film. The test piece is fixed to the grip of the test apparatus so that the distance between the grips is 30 mm. The test piece is elongated in a direction orthogonal to the longitudinal direction of the first region and the second region at a speed of 100 mm / min so that the elongation calculated by the following formula (I) is 80%. The extension ratio (fold) is calculated from the following formula (III). The expansion ratios of twelve randomly selected areas in both the first area and the second area are calculated, and the average value is obtained.
Elongation = (L1-L0) / L0 × 100 (I)
Expansion ratio = R1 / R0 (III)
However, L0 is the distance between grips (mm) before extending, L1 is the distance between grips (mm) after extending, and R0 is the first region or the second before extending. Is a length (μm) in the direction orthogonal to the longitudinal direction of the region (1), and R1 is a length (μm) in the direction orthogonal to the longitudinal direction of the expanded first region or the second region ( However, R0 and R1 are measured at the same location in the same region).

When the average expansion ratio of the first region is equal to or higher than the lower limit value of the above range, the first region is preferentially expanded when the stretchable film is expanded. Therefore, the stretchability of the entire stretchable film becomes good.
If the average expansion ratio of the first region is equal to or less than the upper limit value of the above range, appropriate elasticity can be obtained.
When the average stretch ratio of the second region is within the above range, the permanent strain becomes small and the stretchability of the entire stretchable film becomes good.
In the case of a porous stretchable film, when the average stretch ratio of the second region is within the above range, and the average stretch ratio of the first region is at least the lower limit value of the above range, when stretching the porous stretch film The first region in which the surface layer is broken stretches preferentially. Therefore, the stress applied to the periphery of the through hole is also reduced, and breakage during expansion is less likely to occur. In addition, the second region where the surface layer is not broken has high rigidity and the amount of deformation when the porous stretchable film is stretched is small, so that the breakage is unlikely to occur.

  The width of the first region and the width of the second region before stretching are not particularly limited, and may be appropriately determined depending on the stretchability, air permeability, flexibility and the like required for the stretch film.

(Through hole)
The through hole may be formed in the first region or may be formed in the second region.
Regardless of whether the through hole is formed in the first region or the second region, breakage caused by the through hole is unlikely to occur when the porous stretchable film is stretched. The first region expands with low stress because the surface layer is destroyed. Therefore, the stress applied to the periphery of the through hole is also reduced, and breakage during expansion is unlikely to occur. On the other hand, in the second region, since the surface layer is not broken, the rigidity is high and the deformation during expansion is unlikely to occur, so that the breakage is unlikely to occur.
When the porous stretchable film is manufactured by the manufacturing method of the present invention described later, most of the through holes are formed in the first region.

0.1-1.5 mm < ² > is preferable and, as for the average value of the opening area of a through-hole, 0.2-1.4 mm < ² > is more preferable. When the average value of the opening areas of the through holes is not less than the lower limit value of the above range, the air permeability of the porous stretchable film is further improved. When the average value of the opening area of the through holes is equal to or less than the upper limit value of the above range, breakage caused by the through holes is further unlikely to occur when the porous stretchable film is stretched.
The average value of the opening areas of the through holes is the average value of the opening areas of the 50 through holes randomly selected.

The number of through holes is preferably 1 to 20 and more preferably 3 to 15 per 1 cm ^{2 of the} porous stretchable film. When the number of through holes is at least the lower limit value of the above range, the air permeability of the porous stretchable film will be further improved. When the number of through holes is not more than the upper limit value of the above range, the stretchability of the porous stretchable film is unlikely to decrease.

(Thickness of elastic film)
The thickness of the stretch film is preferably 6 to 70 μm, more preferably 10 to 60 μm, and further preferably 20 to 55 μm. When the thickness of the stretch film is not less than the lower limit of the above range, the stretch film has sufficiently high stretchability. When the thickness of the stretch film is not more than the upper limit value of the above range, the stretchability of the stretch film does not become excessive.

(Action effect)
In the elastic film of the present invention described above, the occurrence of blocking is suppressed because the surface layer is provided on either or both of the first surface and the second surface of the elastomer layer.
Further, in the stretchable film of the present invention described above, in the case of a porous stretchable film having a plurality of through holes, air permeability is good.
Further, in the elastic film of the present invention described above, in the strip-shaped first region extending along the surface direction of the elastic film, the elongation ratio is 1.51 to 5.00 times, and the first region. Stretchable film, which is adjacent to the stretchable film and has a strip-shaped second region that extends along the surface direction of the stretchable film and has a stretch ratio of 1.01 to 1.50 times, which is more difficult to stretch than the first region. The overall stretchability is good. Further, in the case of a porous stretchable film, it is difficult for the porous stretchable film to break when stretched, and the stretchability does not easily decrease. That is, as shown in FIG. 3, when the porous stretchable film 10 is stretched in the TD, the first region 11 that is easier to stretch than the second region 12 preferentially stretches. Therefore, the stretchability of the entire porous stretchable film 10 becomes good despite having the surface layer. Further, in the case of the porous stretchable film 10, since the first region 11 expands with a low stress and the second region 12 has high rigidity and is difficult to expand, breakage caused by the through hole 13 occurs. Hateful. Therefore, the stretchability of the porous stretchable film 10 is less likely to decrease. On the other hand, the stretchability is uniform over the entire surface, and the stretchability is somewhat insufficient because it has a non-stretchable surface layer. When a through hole was formed in a conventional stretchable film, the stretchable film was stretched. At this time, stress is concentrated in the through holes due to insufficient elongation of the film, and the film is easily broken from the through holes.

(Other embodiments)
The stretchable film of the present invention has an elastomer layer and a surface layer provided on one or both of the first surface and the second surface of the elastomer layer, and has a plurality of through holes, and the same through hole is formed. And a first strip-shaped region having a stretch ratio of 1.51 to 5.00 times and a second strip-shaped region having a stretch ratio of 1.01 to 1.50 that is less likely to stretch than the first region. It suffices that it has the regions of 1 and 2 alternately and is not limited to the porous stretchable film 10 of the illustrated example.
For example, the surface layer may be provided on only one of the first surface and the second surface of the elastomer layer.
The through hole does not have to be formed.
The through hole may be formed only in the first region or only in the second region, or may be formed in both the first region and the second region.
The arrangement of the through holes is not limited to the staggered arrangement, and may be a lattice arrangement or a random arrangement.

<Method of manufacturing stretch film>
The method for producing an elastic film of the present invention is a method having the following step (d). The method for producing an elastic film of the present invention may have the step (c). The method for producing a stretchable film of the present invention may have the following step (a) and step (b), if necessary.

Step (a): A step of preparing an elastomer layer forming material and a surface layer forming material.
Step (b): a step of producing an unstretched stretchable film having an elastomer layer and a surface layer provided on one or both of the first surface and the second surface of the elastomer layer.
Step (c): A step of forming a plurality of depressions scattered on the unstretched stretchable film by embossing the unstretched stretchable film, if necessary.
Step (d): A step of obtaining the stretchable film of the present invention by subjecting the unstretched stretchable film to the gear stretching described below after the step (b) or after the step (c).

(Step (a))
When the material for forming the elastomer layer is composed of only the thermoplastic elastomer, the thermoplastic elastomer is used as the material for forming the elastomer layer.
When the elastomer layer forming material contains a thermoplastic elastomer and other components, the respective components are mixed to prepare the elastomer layer forming material. Other components may be masterbatched and added to the material for forming an elastomer layer.

When the surface layer forming material is composed of only the thermoplastic resin, the thermoplastic resin is used as the surface layer forming material.
When the surface layer forming material contains a thermoplastic resin, an inorganic filler and, if necessary, other components, the respective components are mixed to prepare the surface layer forming material. The inorganic filler and other components may be masterbatched and added to the surface layer forming material. When the masterbatch contains a thermoplastic resin, the masterbatch may be used as the surface layer forming material.

Examples of the method for mixing the respective components include a method using various mixers such as a Henschel mixer, a tumbler mixer, a Banbury mixer, and a kneader.
The order of mixing the components is not particularly limited. For example, all components may be mixed at once.
The first surface layer forming material and the second surface layer forming material may be the same material or different materials.

(Step (b))
The elastomer layer-forming material and the surface layer-forming material are molded by a known molding method to form an elastomer layer and a surface layer provided on one or both of the first surface and the second surface of the elastomer layer. An unstretched stretchable film having
Examples of the molding method include a cast film process method and an inflation method, and the cast film process method is preferable from the viewpoint of productivity.

FIG. 4 is a sectional view showing an example of an unstretched stretchable film.
The unstretched stretchable film 10 ′ includes the elastomer layer 14, the first surface layer 15 provided on the first surface of the elastomer layer 14, and the second surface layer provided on the second surface of the elastomer layer 14. 16 and.

In the case of producing a porous stretchable film, the following permanent set of the unstretched stretchable film is preferably 15% or more, more preferably 20% or more.
Unstrained stretch film permanent set:
A strip-shaped test piece of 50 mm in the machine direction (MD) and 200 mm in the width direction (TD) is cut from the unstretched stretchable film. The test piece is fixed to the grip of the test apparatus so that the distance between the grips is 100 mm. The test piece is stretched in TD at a speed of 100 mm / min so that the elongation calculated by the following formula (I) is 80%, and then the test piece is immediately contracted at the same speed. Permanent strain (%) is calculated from the following formula (II).
Elongation = (L1-L0) / L0 × 100 (I)
Permanent strain = (L2-L0) / (L1-L0) × 100 (II)
However, L0 is the distance between grips (mm) before extension, L1 is the distance between grips (mm) after extension, and L2 is the load (N / It is the distance (mm) between the grips when 50 mm) becomes zero.

  If the permanent strain of the unstretched stretchable film is not less than the lower limit of the above range, the shrinkage force of the porous stretchable film is too large after the through holes are formed by the gear stretching in the step (d) through the step (c). Since the permanent strain is not too small, the through holes are not blocked by the shrinkage of the porous stretchable film, and sufficient air permeability can be ensured.

(Process (c))
When producing a porous stretchable film, the unstretched stretchable film is embossed in step (c).
By embossing the unstretched stretchable film, a plurality of depressions scattered in the unstretched stretchable film are formed. The recessed portion is a portion that becomes a through hole when the gear is stretched in the step (d).

Examples of the embossing method include a roll pressing method, a differential pressure method, and a high pressure jet method.
The roll pressing method is a method in which a pin embossing roll having a large number of projecting pins provided on its peripheral surface and an anvil roll corresponding thereto are arranged to face each other, and an unstretched stretchable film is passed between these rolls.
The differential pressure method is a method in which the unstretched stretchable film is softened near the softening temperature and is positioned on the upper surface of the support having a large number of openings, and suction is applied from below the support or air pressure is applied from the upper surface of the support. It is a method of applying pressure.
The high-pressure jet method is a method of deforming an unstretched stretch film by a high-pressure jet of liquid ejected from a large number of high-pressure liquid jet nozzles.

The recessed portion has a depth that does not penetrate the unstretched stretchable film. When a large number of pierced hollow portions are generated, the unstretched stretchable film may be broken during the treatment due to the gear stretching in the step (d).
The depth of the recessed portion can be adjusted, for example, by the height of the protruding pin provided on the pin embossing roll.
The shape, the number, the arrangement, etc. of the protruding pins of the pin embossing roll may be appropriately determined according to the shape, the number, the arrangement, etc. of the through holes of the porous stretchable film.

(Process (d))
After the step (b) or after the step (c), the unstretched stretchable film is gear-stretched to stretch the unstretched stretchable film in a stripe shape, and have first regions and second regions alternately. The elastic film of the present invention is obtained. After the step (c), the unstretched stretchable film is gear-stretched to obtain a porous stretchable film having through holes.
The gear stretching is specifically performed as follows.

  A first shaping roll having a plurality of ridges extending in the circumferential direction or the axial direction, and a second shaping roll having a plurality of ridges extending in the same direction as the ridges of the first shaping roll. The ridges on one of the shaping rolls and the grooves between the ridges on the other shaping roll are arranged so as to face each other.

FIG. 5 is an enlarged view showing an example of a pair of shaping rolls.
The first shaping roll 20 having a plurality of circumferentially extending projections 24 on the circumferential surface of the cylindrical roll body 22 and the plurality of circumferentially extending projections 34 on the circumferential surface of the cylindrical roll body 32 are provided. The second shaping roll 30 has the first shaping roll 30 such that the ridges 24 of the first shaping roll 20 and the grooves 36 between the ridges 34 of the second shaping roll 30 mesh with each other. The grooves 26 between the ridges 24 of the shaping roll 20 and the ridges 34 of the second shaping roll 30 are arranged to face each other with a predetermined clearance so as to mesh with each other.

FIG. 6 is an enlarged view showing another example of the pair of shaping rolls.
The first shaping roll 40 having a plurality of projections 44 extending in the axial direction on the circumferential surface of the cylindrical roll body 42, and the plurality of projections 54 extending in the axial direction on the circumferential surface of the cylindrical roll body 52. The second shaping roll 50 has the first shaping roll 40 such that the ridges 44 of the first shaping roll 40 and the grooves 56 between the ridges 54 of the second shaping roll 50 mesh with each other. The grooves 46 between the ridges 44 of the shaping roll 40 and the ridges 54 of the second shaping roll 50 are opposed to each other with a predetermined clearance so as to mesh with each other.

  By rotating the first shaping roll and the second shaping roll while passing the embossed unstretched stretchable film between the first shaping roll and the second shaping roll, A stretched first region and a non-stretched second region are formed between the ridges of the first shaping roll and the ridges of the second shaping roll. When the unstretched stretchable film is embossed, the first region and the second region are formed, and at the same time, the recessed portion of the unstretched stretchable film is stretched to form a through hole.

According to the pair of shaping rolls in FIG. 5, the unstretched stretchable film passing between them is pushed downward by the ridges 24 of the first shaping roll 20 and the ridges of the second shaping roll 30. Pushed upward by 34. Therefore, the unstretched stretchable film is partially stretched vertically and obliquely by the ridges 24 of the first shaping roll 20 and the ridges 34 of the second shaping roll 30 that are adjacent to each other, and Become. At this time, if a dent exists in the stretched portion of the unstretched stretchable film, the dent is thin and is cleaved by stretching to form a through hole. On the other hand, in the unstretched stretchable film, the portion in contact with the apex of the ridge 24 of the first shaping roll 20 or the apex of the ridge 34 of the second shaping roll 30 is the second region because it is not stretched. .
Since the direction in which the unstretched elastic film is partially stretched by the pair of shaping rolls in FIG. 5 is TD, the gear stretching by the pair of shaping rolls in FIG. 5 is also called TD gear stretching. According to the TD gear stretching, as shown in FIGS. 1 and 2, the strip-shaped first regions 11 extending in the MD and the strip-shaped second regions 12 extending in the MD are alternately formed in the TD.

According to the pair of shaping rolls in FIG. 6, the unstretched stretchable film passing between them is pushed downward by the ridges 44 of the first shaping roll 40 and the ridges of the second shaping roll 50. Pushed upward by 54. Therefore, the unstretched stretchable film is partially stretched vertically and diagonally by the ridges 44 of the first shaping roll 40 and the ridges 54 of the second shaping roll 50 which are adjacent to each other, and the first region Become. At this time, if a dent exists in the stretched portion of the unstretched stretchable film, the dent is thin and is cleaved by stretching to form a through hole. On the other hand, in the unstretched stretchable film, the portion in contact with the top of the ridge 44 of the first shaping roll 40 or the top of the ridge 54 of the second shaping roll 50 is not stretched, and thus becomes the second region. .
Since the direction in which the unstretched stretchable film is partially stretched by the pair of shaping rolls in FIG. 6 is MD, the gear stretching by the pair of shaping rolls in FIG. 6 is also called MD gear stretching. According to the MD gear stretching, band-shaped first regions extending in TD and band-shaped second regions extending in TD are alternately formed in MD.

  When stretching a normal film as a whole, stretching beyond the elastic limit of the film causes irreversible changes in the film. In many cases, the irreversible change of the film is accompanied by a change in color tone (whitening) and a change in dimension (increase or decrease in length or width). This dimensional change is called permanent set. A film in which a permanent strain is generated by stretching which exceeds the elastic limit exhibits elastic behavior within the range of (stretch ratio-permanent strain). For example, when a film having a length of 100 mm is stretched to 200 mm (stretching ratio: 2 times) and a permanent strain of 30% is generated, the length of the stretched film is 130 mm, and 100% -30% = 70%. That is, it has elastic behavior within the range of 130 mm to 200 mm. Here, the elastic behavior refers to the property of returning to the original dimension when the force is removed even if the dimension changes due to the application of force. Since the length of the stretched film has changed from 100 mm before stretching to 130 mm, the stretched film exhibits elastic behavior within the range of 100% to 154% (130 mm / 130 mm to 200 mm / 130 mm) (elasticity). Have).

In gear stretching, the unstretched stretchable film is partially stretched beyond its elastic limit. An unstretched stretchable film stretched partially beyond its elastic limit by gear stretching causes a change in color tone. That is, the first region of the white portion in FIGS. 1 and 2 is a region that has been stretched beyond the elastic limit and generated permanent strain, resulting in elasticity in a certain range. This change in color tone indicates that the structure of the unstretched stretchable film undergoes an irreversible change. For example, when the unstretched stretchable film has a surface layer containing a non-elastomer thermoplastic resin (polyethylene, polypropylene, etc.), the surface layer is stretched and broken by stretching beyond the elastic limit. Voids such as cracks and fine holes are generated inside the stretched and destroyed surface layer. These voids cause diffuse reflection of light that has entered the surface layer, and appear white in appearance. Further, the destroyed surface layer loses its original mechanical strength. Along with this, the first region is released from the constraint of the surface layer, and its original elasticity (stretchability due to the elastomer layer) comes to be expressed.
The color tone does not change in the portion that is not stretched by the gear stretching, that is, the second region.

In the gear stretching, the width W of the top of the ridge of the shaping roll, the height H of the ridge, the interval P between the tops of the adjacent ridges, the ridge of the first shaping roll and the second shaping The draw ratio can be adjusted by adjusting the engagement depth D of the roll with the ridge.
The stretching ratio in gear stretching can be easily calculated from the stretching principle by the Pythagorean theorem. For example, the distance between the tops of the ridges of the adjacent first shaping rolls and the tops of the ridges of the second shaping rolls (width of the stretched portion of the unstretched stretchable film) is 1 mm, and the engagement depth is When it was √3 mm, the width of the stretched portion of the unstretched stretchable film was 2 mm, and the stretch ratio was 2 times. Here, when the permanent set is 30%, the width of the stretched portion changes from 1 mm before stretching to 1.3 mm.

The width of the first region and the width and length of the second region are not particularly limited and may be appropriately determined according to the purpose of use of the stretch film and the like.
The area of the opening of the through hole can be appropriately adjusted depending on the size and shape of the protruding pin of the pin embossing roll and the stretching ratio.

(Action effect)
In the method for producing a stretchable film of the present invention described above, the unstretched stretchable film having the surface layer provided on one or both of the first surface and the second surface of the elastomer layer is described above. Since the gear is stretched, it is possible to manufacture an elastic film having the width of the first region and the second region. That is, it is possible to produce an elastic film in which the occurrence of blocking is suppressed and the elasticity is good.
Further, by embossing the unstretched stretchable film to form a plurality of depressions scattered in the unstretched stretchable film, and when the embossed unstretched stretchable film is gear-stretched as described above, the first region A porous stretchable film having a width and a second region and having through holes can be manufactured. That is, it is possible to produce a porous stretchable film in which blocking is suppressed, air permeability is good, and stretchability is good.

(Other embodiments)
Among the stretchable films of the present invention, the porous stretchable film may be manufactured by a manufacturing method other than the method of combining embossing and gear stretching.
For example, an unstretched stretchable film that has not been embossed is gear-stretched to form a first region and a second region, and then a through hole is formed by a known opening means (slitting, hot pin melt, etc.). Good.

<Composite sheet>
The composite sheet of the present invention has a layer made of the stretchable film of the present invention and a layer made of a nonwoven fabric.

(Nonwoven fabric)
Examples of the non-woven fabric include spun bond non-woven fabric, melt blown non-woven fabric, flash spun non-woven fabric, chemical bond non-woven fabric, thermal bond non-woven fabric, wet non-woven fabric and dry non-woven fabric.
Examples of the fibers of the non-woven fabric include synthetic fibers (polypropylene fibers, polyamide fibers, polyester fibers, etc.), natural fibers (cotton, silk), semi-synthetic fibers (rayon fibers, acetate fibers, etc.) and the like.
The non-woven fabric may be subjected to a stretch imparting process (softening process, pleating process, shrinking process, filling process, etc.).

(Method for manufacturing composite sheet)
The composite sheet is produced by, for example, joining the stretchable film of the present invention and the nonwoven fabric and laminating them.
Examples of the joining method include a hot pressing method, a hot embossing bonding method, a bonding method using a hot melt adhesive, an ultrasonic bonding method, and a high frequency bonding method.

(Action effect)
Since the composite sheet of the present invention described above has the layer made of the stretchable film of the present invention, the occurrence of blocking due to the layer made of the stretchable film is suppressed and the stretchability is good.
Further, in the above-described composite sheet of the present invention, when the elastic film of the present invention is a porous elastic film, air permeability is good.

(Other embodiments)
The composite sheet of the present invention only needs to have a layer made of the stretchable film of the present invention and a layer made of a nonwoven fabric, and is not limited to a layer made of the stretchable film of the present invention and a layer made of a nonwoven fabric. Not done.
For example, as long as the effect of the composite sheet of the present invention is not impaired, it may have a layer other than the layer made of the stretchable film of the present invention and the layer made of the nonwoven fabric.

  Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following description.

<Measurement method, evaluation method>
(Thickness of each layer)
The thicknesses of the elastomer layer and the surface layer in the unstretched stretchable film were determined by observing the cross section with a microscope.

(Permanent strain of stretch film)
A strip-shaped test piece of 50 mm in the machine direction (MD) and 200 mm in the width direction (TD) was cut from the elastic film. The test piece was fixed to a grip of a precision universal tester (manufactured by Shimadzu Corporation, Autograph, material test operation software: TRAPEZIUM2) so that the distance between the grips was 100 mm. The test piece was stretched in TD at a speed of 100 mm / min so that the elongation calculated by the following formula (I) was 80%, and then the test piece was immediately shrunk at the same speed. The permanent strain (%) at the first cycle was calculated from the following formula (II). The same operation was repeated once again using the test piece used in the first cycle to calculate the permanent set (%) in the second cycle. The test was performed at 23 ° C ± 2 ° C.
Elongation = (L1-L0) / L0 × 100 (I)
Permanent strain = (L2-L0) / (L1-L0) × 100 (II)
However, L0 is the distance between grips (mm) before extension, L1 is the distance between grips (mm) after extension, and L2 is the load (N / It is the distance (mm) between the grips when 50 mm) becomes zero.

(Breathability of stretch film)
Regarding the stretchable film, in accordance with JIS P 8117: 2009 (ISO 5636-5: 2003), a Gurley type densometer (manufactured by Toyo Seiki Seisakusho Ltd., G-B3C type) was used to measure the time taken for 100 mL of air to pass through, The air resistance (second / 100 mL) was used. The air permeability resistance is an index of air permeability. The lower the air resistance, the better the air permeability. The lower detection limit is 1.4 seconds / 100 mL.

(Average expansion ratio of the first area and the second area)
A strip-shaped test piece of 50 mm in the machine direction (MD) and 100 mm in the width direction (TD) was cut from the stretch film. The test piece was fixed to a grip of a precision universal tester (manufactured by Shimadzu Corporation, Autograph, material test operation software: TRAPEZIUM2) so that the distance between the grips was 30 mm. The test piece was stretched in TD at a speed of 100 mm / min so that the elongation calculated by the following formula (I) was 80%. The extension ratio (fold) was calculated from the following formula (III). The extension ratios of 12 randomly selected regions in both the first region and the second region were calculated, and the average value was obtained. The test was performed at 23 ° C ± 2 ° C.
Elongation = (L1-L0) / L0 × 100 (I)
Expansion ratio = R1 / R0 (III)
However, L0 is the distance between grips (mm) before extending, L1 is the distance between grips (mm) after extending, and R0 is the first region or the second before extending. Is a length (μm) in the direction orthogonal to the longitudinal direction of the region (1), and R1 is a length (μm) in the direction orthogonal to the longitudinal direction of the expanded first region or the second region ( However, R0 and R1 are measured at the same location in the same region).

<Raw material>
(Thermoplastic elastomer)
Vistamaxx (registered trademark) 6102 (manufactured by ExxonMobil, propylene-ethylene copolymer, glass transition temperature: -32 ° C, ethylene unit content: 16% by mass).
(Thermoplastic resin)
Sumikasen (registered trademark) CE3506 (polyethylene manufactured by Sumitomo Chemical Co., Ltd.).
(Master Badge)
TEP 1HC783 WHT (manufactured by HANIL TOYO, calcium carbonate (average particle diameter: 5 μm, content rate: 50 mass%), base resin: polyethylene).

(Material for forming elastomer layer)
As the elastomer layer forming material (A-1), a thermoplastic elastomer was used as it was.
(Material for forming surface layer)
As the surface layer-forming material (B-1), a mixture of 85% by mass of polyethylene and 15% by mass of calcium carbonate, which was obtained by mixing a thermoplastic resin and a masterbatch with a tumbler mixer, was used.
The masterbatch was used as it was as the surface layer forming material (B-2).

<Production of unstretched stretchable film>
(Production Example 1)
Using an extruder equipped with a T-die (manufactured by Sumitomo Heavy Industries Modern Co., Ltd.), the elastomer layer forming material (A-1) and the surface layer forming material (B-1) are extrusion-molded at 200 ° C. and cast film process. Unstretched stretchable film having an elastomer layer, a first surface layer provided on the first surface of the elastomer layer, and a second surface layer provided on the second surface of the elastomer layer (F -1) was obtained. The thickness of each layer is shown in Tables 1 and 2.

(Production Example 2)
The elastomer layer and the first surface of the elastomer layer were provided in the same manner as in Production Example 1 except that the surface layer forming material (B-1) was changed to the surface layer forming material (B-2). An unstretched stretchable film (F-2) having a first surface layer and a second surface layer provided on the second surface of the elastomer layer was obtained. The thickness of each layer is shown in Tables 3 and 4.

<Production of porous stretchable film or stretchable film>
(Example 1)
The unstretched stretchable film (F-1) was embossed by a roll pressing method.
The shape of the protruding pins provided on the pin embossing roll was a cylinder (diameter: 0.5 mm, height: 0.8 mm), and the protruding pins were arranged in a staggered arrangement with an interval of 3 mm.

The unstretched stretchable film that had been embossed was subjected to TD gear stretching using a pair of shaping rolls as shown in FIG. 5 to obtain a porous stretchable film. The porous stretchable film was evaluated. The results are shown in Table 1.
In the TD gear stretching, the width of the top of the ridge of the first shaping roll is 0.5 mm, and the width of the top of the ridge of the second shaping roll is 0.5 mm. The distance between the tops of the ridges is 2.5 mm, the distance between the tops of the ridges of the first shaping roll is 2.5 mm, and the ridges of the first shaping roll and the second shaping roll are The depth of engagement with the ridges was set to 2.9 mm (210%).

(Example 2)
A stretch film was obtained in the same manner as in Example 1 except that TD gear stretching was performed without embossing. The stretchable film was evaluated. The results are shown in Table 1.

(Comparative Example 1)
An elastic film was obtained in the same manner as in Example 1 except that embossing was performed and TD gear stretching was not performed. The stretchable film was evaluated. The results are shown in Table 1.

(Comparative example 2)
The unstretched stretchable film (F-1) was evaluated. Table 2 shows the results.

(Comparative Example 3)
Slits were formed in the unstretched stretch film (F-1) by slitting to obtain a porous stretch film. The porous stretchable film was evaluated. Table 2 shows the results.

(Comparative example 4)
Through holes were formed in the unstretched stretch film (F-1) by hot pin melt to obtain a porous stretch film. The porous stretchable film was evaluated. Table 2 shows the results.

(Example 3)
A porous stretchable film was obtained in the same manner as in Example 1 except that the unstretched stretchable film (F-2) was used. The porous stretchable film was evaluated. The results are shown in Table 3.
However, in the TD gear stretching, the engagement depth between the ridges of the first shaping roll and the ridges of the second shaping roll was set to 3.2 mm (240%).

(Example 4)
An elastic film was obtained in the same manner as in Example 3 except that TD gear stretching was performed without embossing. The stretchable film was evaluated. The results are shown in Table 3.

(Comparative example 5)
An elastic film was obtained in the same manner as in Example 3 except that embossing was performed and TD gear stretching was not performed. The stretchable film was evaluated. The results are shown in Table 3.

(Comparative example 6)
The unstretched stretchable film (F-2) was evaluated. The results are shown in Table 4.

(Comparative Example 7)
Slits were formed in the unstretched stretchable film (F-2) by slitting to obtain a porous stretchable film. The porous stretchable film was evaluated. The results are shown in Table 4.

(Comparative Example 8)
Through holes were formed in the unstretched stretch film (F-2) by hot pin melt to obtain a porous stretch film. The porous stretchable film was evaluated. The results are shown in Table 4.

From the results of Examples 1 and 3, it can be seen that the unstretched stretchable film is embossed and gear-stretched to form the first region and the second region, and at the same time, the through hole is formed. The porous stretchable film having the first region and the second region and having the through holes formed therein has a small permanent strain (good stretchability) and high air permeability.
From the results of Examples 2 and 4, it can be seen that the first region and the second region are formed by the gear stretching of the unstretched stretchable film without embossing, but the through hole is not formed. The stretchable film having the first region and the second region has a small permanent set (good stretchability).
From the results of Comparative Examples 1 and 5, it is understood that the first region and the second region and the through hole are not formed only by embossing the unstretched stretchable film. Moreover, it is understood that the permanent strain is relatively large and the elasticity is insufficient.
From the results of Comparative Examples 2 and 6, it can be seen that the unstretched stretchable film itself has a relatively large permanent strain (insufficient stretchability) and does not have air permeability.
From the results of Comparative Examples 3, 4, 7, and 8, if the slits or through holes were formed in the unstretched stretch film by slitting or hot melt, stress was concentrated in the slits or through holes when the stretch film was stretched. It turns out that it breaks.

  The elastic film and the composite sheet of the present invention are preferably used in the hygiene and medical fields. For example, it is used for elastic paper diaper tabs, side panels for training pants, leg gathers, sanitary items, swimming pants, incontinence items, veterinary items, bandages, surgical clothes, surgical drapes, sterile covers, wipes, and the like.

10 Porous stretch film,
10 'unstretched stretch film,
11 First area,
12 Second area,
13 through holes,
14 elastomer layer,
15 first surface layer,
16 second surface layer,
20 first shaping roll,
22 roll body,
24 ridges,
26 grooves,
30 second shaping roll,
32 roll body,
34 ridge,
36 grooves,
40 first shaping roll,
42 roll body,
44 ridge,
46 grooves,
50 Second shaping roll,
52 roll body,
54 ridge,
56 groove.

Claims (7)

A film-like elastomer layer comprising a thermoplastic elastomer, elastomer layer provided on both the first and second surfaces of, and a surface layer comprising a thermoplastic resin (. Excluding the thermoplastic elastomer) It is an elastic film that has,
The elastic film is adjacent to the strip-shaped first region in which the surface layer is broken and extends along the surface direction of the elastic film, is adjacent to the first region, and is less likely to extend than the first region. , Alternately having strip-shaped second regions extending along the surface direction of the stretch film,
The following average elongation ratio of the first region is 1.51 to 5.00 times,
An elastic film in which the following average elongation ratio of the second region is 1.01 to 1.50 times.
(Average elongation rate)
A strip-shaped test piece of 50 mm in the longitudinal direction of the first region and the second region and 100 mm in the direction orthogonal to the longitudinal direction is cut out from the elastic film. The test piece is fixed to the grip of the test apparatus so that the distance between the grips is 30 mm. The test piece is elongated in a direction orthogonal to the longitudinal direction of the first region and the second region at a speed of 100 mm / min so that the elongation calculated by the following formula (I) is 80%. The extension ratio (fold) is calculated from the following formula (III). The expansion ratios of twelve randomly selected areas in both the first area and the second area are calculated, and the average value is obtained.
Elongation = (L1-L0) / L0 × 100 (I)
Expansion ratio = R1 / R0 (III)
However, L0 is the distance between grips (mm) before extending, L1 is the distance between grips (mm) after extending, and R0 is the first region or the second before extending. Is a length (μm) in the direction orthogonal to the longitudinal direction of the region (1), and R1 is a length (μm) in the direction orthogonal to the longitudinal direction of the expanded first region or the second region ( However, R0 and R1 are measured at the same location in the same region).   The stretchable film according to claim 1, which is a porous stretchable film having a plurality of through holes formed therein.   The stretchable film according to claim 1, wherein the surface layer further contains an inorganic filler. A method for producing the stretchable film according to any one of claims 1 to 3,
A first shaping roll having a plurality of ridges extending in the circumferential direction or the axial direction, and a second shaping roll having a plurality of ridges extending in the same direction as the ridges of the first shaping roll. , The first shaping roll and the second shaping roll, while the ridges of one of the shaping rolls and the grooves between the ridges of the other shaping roll are arranged to face each other so as to mesh with each other and are rotated. By passing the following unstretched stretchable film between and, the first region and the stretched between the ridges of the first shaping roll and the ridges of the second shaping roll. A method for producing a stretchable film, which includes the step (d) of forming the second region that has not been formed.
(Unstretched elastic film)
An elastomer layer containing a thermoplastic elastomer, and a surface layer containing a thermoplastic resin (excluding the thermoplastic elastomer) provided on one or both of the first surface and the second surface of the elastomer layer. An unstretched stretchable film having. Prior to the step (d), the method further includes a step (c) of forming a plurality of depressions scattered on the unstretched stretchable film by embossing the unstretched stretchable film,
In the step (d), the first region stretched between the ridges of the first shaping roll and the ridges of the second shaping roll and the second region not stretched. The method for producing a stretchable film according to claim 4, wherein, at the same time as forming the film, the recess is stretched to form a through hole. The method for producing an elastic film according to claim 5, wherein the following permanent set of the unstretched elastic film is 15% or more.
(Permanent strain of unstretched stretch film)
A strip-shaped test piece of 50 mm in the machine direction (MD) and 200 mm in the width direction (TD) is cut from the unstretched stretchable film. The test piece is fixed to the grip of the test apparatus so that the distance between the grips is 100 mm. The test piece is stretched in TD at a speed of 100 mm / min so that the elongation calculated by the following formula (I) is 80%, and then the test piece is immediately contracted at the same speed. Permanent strain (%) is calculated from the following formula (II).
Elongation = (L1-L0) / L0 × 100 (I)
Permanent strain = (L2-L0) / (L1-L0) × 100 (II)
However, L0 is the distance between grips (mm) before extension, L1 is the distance between grips (mm) after extension, and L2 is the load (N / It is the distance (mm) between the grips when 50 mm) becomes zero.   A composite sheet comprising a layer made of the stretchable film according to any one of claims 1 to 3 and a layer made of a nonwoven fabric.